1. Department of Urology, Charing Cross Hospital, Imperial College Healthcare NHS Trust, Fulham Palace Rd, London W6 8RF, UK
2. Department of Urology, West Middlesex University Hospital, Chelsea and Westminster Hospital NHS Foundation, Twickenham Rd, Isleworth TW7 6AF, UK
3. Department of Urology, Swansea Bay University Health Board, Swansea SA6 6NL, UK
4. Department of Urology, Dartford and Gravesham NHS Trust, Dartford DA2 8DA, UK